Gerber Beam (Wood) Calculator, NDS 2018

What it checks

The module designs a Gerber (drop-in) beam in glulam that is continuous over its supports with internal hinges making it determinate. It uses NDS 2018 §3.3 for glulam design, specifically referencing Table 5A layup values. The engine performs a statics analysis to locate the hinge position that minimizes the governing moment. The design method involves searching for the hinge position that yields the smallest governing moment, which is the larger of the largest sagging moment in the spans and the largest hogging moment over the supports. The module runs the whole analysis at every candidate position to determine the optimal layout. The sequence of checks begins by defining the girder with its supports, hinges, and loads by case. The locator then moves each hinge to the position with the smallest governing moment. Finally, the module reports the envelope of the arrangement, including the specific moment values and shear forces at the best position.

Inputs

Geometry - The girder drawn with its supports, hinges, and nodes.
Loads - Global loads applied by case to the beam model.
Search Parameters - Margin in feet (ft) for the closest a hinge may sit to the node on either side, and the number of passes for sweeps over the hinges.
Material - Glulam layup values from Table 5A, such as 24F-V8.

What it reports

Governing Moment - The larger of the largest sagging and hogging moments, in kip-ft, which the search minimizes.
Sagging Moment - The largest sagging moment in the spans, in kip-ft.
Hogging Moment - The largest hogging moment magnitude over the supports, in kip-ft.
Hinge Shear - The shear carried across the hinge at the best position, representing the hinge connector's demand, in kips.
Search Range - The stretch in feet (ft) the hinge was allowed to move in.
Position Scan - The governing moment against hinge position, with other hinges held at their best, provided as pairs of position and moment in kip-ft.
Final Model - The beam model with hinges at their best positions and loads re-laid on it.

Code references

The engine cites NDS 2018 §3.3 for glulam design, utilizing Table 5A layup values. Statics are handled by the engine, with the hinge position determined through a search process.

Limits

The module assumes the beam is a Gerber (drop-in) girder that is continuous over its supports with internal hinges making it determinate. It does not handle cases where the hinge position does not minimize the governing moment, as the search specifically targets the smallest governing moment. The number of passes only matters when two hinges share a span. Results are engineering aids; the engineer of record is responsible for the design.

This module ships in the desktop app

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